This invention is directed generally to latch constructions for securing separable base and cover members of a receptacle or container in closed condition, and is more particularly directed to molded plastic latch constructions for molded plastic receptacles. The invention constitutes an improvement over the latch construction shown in my prior U.S. Pat. No. 3,730,576.
As discussed in the foregoing patent, blow molding of separate receptacle base and cover members provides an effective and economical way of fabricating a separable closure for a variety of articles. Particularly where the molded members are of the conventional double-wall construction, the blow molding technique provides an excellent way of matching the configuration of the receptacle base and cover to the particular shape of the article or articles to be contained. The double-wall construction facilitates receptacle design of suitably smooth or regular exterior surface, yet may be configured internally to produce retaining wells or abutments to accommodate the contour of the article contained, so as to securely restrain it against movement within the receptacle when closed. This is of great advantage for packaging tools, test instruments, electronic equipment and the like which are subject to damage during storage and transport. Double-wall constructions also provide a shock resistant cushion against damage to contained articles if the receptacle is dropped or is exposed to sudden contact with surrounding objects. The trade is familiar with these and other advantages of double-walled blow molded receptacles, but experience has indicated the desirability of further improvement in the latch constructions which have previously been used to maintain the cover and base members in closed condition. A need for improved latch constructions is indicated in not only maintaining the economical compatibility of the previous constructions with blow molded containers, but in giving greater assurance against accidental detachment or failure under load. In the latch construction disclosed in my aforesaid patent, the means for securing the latching buckle to the receptacle employs a latch anchor bar on the container and a continuous slot in the buckle, with interference nibs along opposite sides of the slot which snap over the head of the anchor bar. Resilient compressibility of the plastic material of the head of the anchor bar and nibs of the buckle is relied upon to permit the attachment to be made. But this inherent resiliency of the plastic also allows for detachment to occur, so a compromise must be made in determining the degree of interference to permit attachment yet resist detachment.
It is accordingly an object of this invention to provide an improved latch construction of the type and for the purpose above indicated, it being particularly desired to provide a latch which is more secure against accidental detachment, particularly under stress, than has been available heretofore but which is nevertheless simple and economical to make, and is also easily assembled to the container or receptacle which it serves to keep in closed condition. These and other objects will become apparent from the following description of a preferred latch construction incorporating the characterizing features of this invention, as embodied in a double wall, blow molded receptacle shown in the accompanying drawings.